These House Rules apply to ALL of my games. Any time I'm GMing, this is what you can expect.
3 Session rule -
The way I see it, if you have never played a particular game before, then how can you be expected to know what kind of character you want to play? Anytime I have a player that's new to the game, I usually give them 3 sessions to decide what they want to play. They can make minor stat adjustments, or throw their character sheet away and start from scratch, and they suffer no XP penalty- just transfer all experience points to the new character. Naturally, you can't decide you want to change your character in the middle of combat, but anytime between sessions is fine by me. Once the fourth session begins, you better have your character the way you like it, becuase any change from that point on will incur an XP penalty.
Play nice -
It is the players' responsibility to have their characters get along with eachother. I'm not your mother, and I don't want to spend game time trying to coax your characters to behave. If you made a character whose family was slain by elves, and has an intense hatred of all things elvish, then I suggest you change your background if another player wants to play an elf. I don't want to deal with it.
Call ahead -
If, for some reason, you are unable to show up for a session, then pick up a phone and give either the GM or one of the players a heads-up. I can't even count the number of times my games have been postponed for 2 or 3 hours while I just sat around twiddling my thumbs waiting for people to show up. I don't expect people to make every session, but I do expect people to call ahead when there's been a change of plans.
Bringing friends -
Few things piss me off like having extra players drop by unanounced. I really don't have a problem with you inviting friends to join in the game, BUT you need to be considerate of both the GM and of the other players. Just becuase you get along with your friend doesn't mean the rest of us will. Any time you want to invite a friend to join the game, you must follow these simple steps:
1) Ask the GM. The GM may not want any more players, or may ask you to wait until the current story arc is over.
2) Ask the host. Never invite ANYONE over to someone else's home. That's just plain rude. If you're playing the game at a friend's house, you need to clear it with him first.
3) The new player will be considered a temporary player (usually assigned an NPC to play) for a couple of sessions until the rest of the players decide they want him to join the game. It's real simple- nobody wants to play with someone they don't like. Even if the GM and most of the players like the guy, all it takes is one personality clash to ruin a game.
Pick up after yourself -
When the session is over, before you go home, take a minute to look around and make sure you throw away all your trash. I don't expect you to vacuum the carpet or wipe down the kitchen counters, but if you see any of your soda cans, chip bags, or scrap paper lying around, then do me a favor and throw it out, ok?